The turbine assembly can be subjected to increased heat loads when an engine is operating. To protect the turbine assembly components from damage, cooling fluid may be directed in and/or onto the turbine assembly. Component temperature can then be managed through a combination of impingement onto, cooling flow through passages in the component, and film cooling with the goal of balancing component life and turbine efficiency. Improved efficiency can be achieved through increasing the firing temperature, reducing the cooling flow, or a combination.
One issue with cooling known turbine assemblies is inadequate cooling on squealer tips of turbine blades. The rail of the squealer tip is subjected to high heat loads, making the rail one of the hottest regions of the turbine blade. Furthermore, the rail of the squealer tip frequently rubs against other components within the turbine assembly during operation, potentially causing cooling holes or slots placed through the rail to plug. Plugged cooling holes may prevent coolant from flowing through the rail, thus causing the surface temperatures of the rail to remain excessively high, which increases the total heat load of the turbine assembly and may reduce part life below acceptable levels or require use of additional cooling fluid. Therefore, an improved system may provide improved cooling coverage and thereby reduce the average and/or local surface temperature of critical portions of the turbine assembly, enable more efficient operation of the engine, and/or improve the life of the turbine machinery.